On Wed, Oct 25, 2023 at 12:23:10PM +0300, Dmitry Baryshkov wrote: > While developing and testing the commit bfcc3d8f94f4 ("drm/msm/dp: > support setting the DP subconnector type") I had the patch [1] in my > tree. I haven't noticed that it was a dependency for the commit in > question. Mea culpa. This also broke boot on the Lenovo ThinkPad X13s. Would be nice to get this fixed ASAP so that further people don't have to debug this known regression. > Since the patch has not landed yet (and even was not reviewed) > and since one of the bridges erroneously uses USB connector type instead > of DP, attach the property directly from the MSM DP driver. > > This fixes the following oops on DP HPD event: > > drm_object_property_set_value (drivers/gpu/drm/drm_mode_object.c:288) > dp_display_process_hpd_high (drivers/gpu/drm/msm/dp/dp_display.c:402) > dp_hpd_plug_handle.isra.0 (drivers/gpu/drm/msm/dp/dp_display.c:604) > hpd_event_thread (drivers/gpu/drm/msm/dp/dp_display.c:1110) > kthread (kernel/kthread.c:388) > ret_from_fork (arch/arm64/kernel/entry.S:858) This only says where the oops happened, it doesn't necessarily in itself indicate an oops at all or that in this case it's a NULL pointer dereference. On the X13s I'm seeing the NULL deref in a different path during boot, and when this happens after a deferred probe (due to the panel lookup mess) it hangs the machine, which makes it a bit of a pain to debug: Unable to handle kernel NULL pointer dereference at virtual address 0000000000000060 ... CPU: 4 PID: 57 Comm: kworker/u16:1 Not tainted 6.7.0-rc1 #4 Hardware name: Qualcomm QRD, BIOS 6.0.220110.BOOT.MXF.1.1-00470-MAKENA-1 01/10/2022 ... Call trace: drm_object_property_set_value+0x0/0x88 [drm] dp_display_process_hpd_high+0xa0/0x14c [msm] dp_hpd_plug_handle.constprop.0.isra.0+0x90/0x110 [msm] dp_bridge_atomic_enable+0x184/0x21c [msm] edp_bridge_atomic_enable+0x60/0x94 [msm] drm_atomic_bridge_chain_enable+0x54/0xc8 [drm] drm_atomic_helper_commit_modeset_enables+0x194/0x26c [drm_kms_helper] msm_atomic_commit_tail+0x204/0x804 [msm] commit_tail+0xa4/0x18c [drm_kms_helper] drm_atomic_helper_commit+0x19c/0x1b0 [drm_kms_helper] drm_atomic_commit+0xa4/0x104 [drm] drm_client_modeset_commit_atomic+0x22c/0x298 [drm] drm_client_modeset_commit_locked+0x60/0x1c0 [drm] drm_client_modeset_commit+0x30/0x58 [drm] __drm_fb_helper_restore_fbdev_mode_unlocked+0xbc/0xfc [drm_kms_helper] drm_fb_helper_set_par+0x30/0x4c [drm_kms_helper] fbcon_init+0x224/0x49c visual_init+0xb0/0x108 do_bind_con_driver.isra.0+0x19c/0x38c do_take_over_console+0x140/0x1ec do_fbcon_takeover+0x6c/0xe4 fbcon_fb_registered+0x180/0x1f0 register_framebuffer+0x19c/0x228 __drm_fb_helper_initial_config_and_unlock+0x2e8/0x4e8 [drm_kms_helper] drm_fb_helper_initial_config+0x3c/0x4c [drm_kms_helper] msm_fbdev_client_hotplug+0x84/0xcc [msm] drm_client_register+0x5c/0xa0 [drm] msm_fbdev_setup+0x94/0x148 [msm] msm_drm_bind+0x3d0/0x42c [msm] try_to_bring_up_aggregate_device+0x1ec/0x2f4 __component_add+0xa8/0x194 component_add+0x14/0x20 dp_display_probe+0x278/0x41c [msm] > [1] https://patchwork.freedesktop.org/patch/555530/ > > Fixes: bfcc3d8f94f4 ("drm/msm/dp: support setting the DP subconnector type") > Reviewed-by: Abhinav Kumar <quic_abhinavk@xxxxxxxxxxx> > Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx> Reviewed-by: Johan Hovold <johan+linaro@xxxxxxxxxx> Tested-by: Johan Hovold <johan+linaro@xxxxxxxxxx> Johan